Can you check my work on this geometry question ? !

question: determine if triangle rst with coordinates r(2, 3), s(4, 4), and t(5, 0) is a right triangle. use evidence to support your claim.

my so first i will do the slope formula on r and s.
(2,3)=r (4,4)=s
the slope formula is (y2-y1)/(x2-
(4-3)/(4-2)
the answer to this one is 1/2.

next: r and t.
(2,3)=r (5,0)=t
using the same formula, i will apply it to rt.
(0-3)/(5-2)
the answer to this is -3/3.

finally: s and t.
(4,4)=s (5,0)=t
using the same formula like before, i use it on st.
(0-4)/(5-4)
the answer i got is: -4/1

because of none of the lines being perpendicular (which would make a right triangle), i determined that this is not a right triangle.

am i right? did i do the steps in an understandable manner? did i miss anything? and